U.S. patent number 4,023,570 [Application Number 05/678,796] was granted by the patent office on 1977-05-17 for adhesively attached absorbent liners.
This patent grant is currently assigned to Personal Products Company. Invention is credited to Kays Chinai, James A. Ginocchio.
United States Patent |
4,023,570 |
Chinai , et al. |
May 17, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Adhesively attached absorbent liners
Abstract
A protective absorbent liner for nether garments is provided
comprising an elongated absorbent body having the body contacting
major surface and a garment contacting major surface. Pressure
sensitive adhesive element means are disposed longitudinally and
centrally upon the garment contacting surface and extend from end
to end thereof. The removable release strip overlies the entire
length of the pressure sensitive adhesive element. At least one
extreme end portion of the pressure sensitive adhesive element is
provided with a pattern of raised and depressed areas whereby the
resistance to peeling of both the release strip prior to use and
the nether garment after use is lower in the end portion than in
the central portion of the adhesive element.
Inventors: |
Chinai; Kays (Burlington,
NJ), Ginocchio; James A. (Summit, NJ) |
Assignee: |
Personal Products Company
(Milltown, NJ)
|
Family
ID: |
24724305 |
Appl.
No.: |
05/678,796 |
Filed: |
April 21, 1976 |
Current U.S.
Class: |
604/370; D24/125;
604/369; 604/374; 604/390; 604/387 |
Current CPC
Class: |
A61F
13/58 (20130101); A61F 13/5611 (20130101) |
Current International
Class: |
A61F
13/58 (20060101); A61F 13/56 (20060101); A61F
013/16 () |
Field of
Search: |
;128/29R,29W,287,284 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Lipow; Jason
Claims
We claim:
1. A protective absorbent liner for nether garments comprising:
an elongated absorbent body having a body contacting major surface
and a garment contacting major surface;
means for securing said liner to the interior of the crotch portion
of said nether garment, said means comprising a pressure sensitive
adhesive element disposed upon said garment contacting surface and
extending longitudinally and substantially, from end to end on said
garment contacting surface;
a removable protective release strip overlying said pressure
sensitive adhesive element;
at least one end portion of said pressure sensitive adhesive
elements being provided with a pattern of raised and depressed
areas whereby the resistance to peeling of both the the release
strip and the nether garment is lower in said end portion than in
the central portion of said adhesive element.
2. The protective liner of claim 1 wherein the portion of said
release strip overlying the at least one extreme end portion of
said pressure sensitive adhesive element rest on said raised
area.
3. The protective liner of claim 1 wherein both extreme end
portions of said pressure sensitive adhesive element are provided
with said pattern of raised and depressed areas.
4. The protective liner of claim 1 wherein said raised areas
comprise about 1.0 to about 30% of the total adhesive area provided
with said pattern.
5. The protective liner of claim 4 wherein said raised areas
comprise about 5.0 to about 20% of the total adhesive area provided
with said pattern.
6. The protective absorbent liner of claim 1 wherein said absorbent
body comprises an absorbent material having a fluid impervious
layer overlying and adhered to the garment contacting major
surface.
7. The protective absorbent liner of claim 6 wherein said fluid
impervious layer is polyethylene film.
Description
BACKGROUND OF THE INVENTION
This invention relates to absorbent nether garment liners such as
sanitary napkins and panty shields and more specifically, to such
products which employ adhesive means for attaching the product to
the crotch portion of a nether garment when in use. Such products
are provided to absorb and retain body fluids and to protect the
nether garment from staining and soiling. The prior art is now
replete with suggestions for absorbent liners comprising an
absorbent body having garment and body contacting major surfaces
and provided with pressure sensitive adhesive means on the garment
contacting surface for adherence of the product to a nether
garment. Generally, these liners are provided with a protective
release strip overlying the pressure sensitive adhesive element and
protecting it from dirt and unintentional adhesion when packaged,
stored and handled prior to use. At the time of use, the strip is
peeled from the adhesive means and the product is positioned and
adhered to the undergarment. After use, the product is peeled from
the undergarment and disposed of.
The adhesive system employed in such products must meet several
sometimes conflicting criteria. In use, it is important that the
product adhere tenaciously to the undergarment at all times and so
the adhesive system must resist moisture, the sudden torques
exerted by movements of the body and the frictional shearing forces
exerted by the movements of the various layers of clothing worn by
the user. Notwithstanding the adherence tenacity required of the
adhesive system during use, it is important tha the protective
strip be easily peeled from the adhesive prior to use without
tearing or delaminating the product. After use, it is essential
that the product be easily peeled from the undergarment, again
without tearing or delaminating the product or, in this case,
without doing damage to the fabric of the undergarment. In view of
the fact that after use, the product is generally soiled, it is
important that the user can easily and quickly grip the product and
peel it from the garment without undue fumbling or effort.
Several solutions have been offered to this problem of providing
in-use tenacity in combination with facile peelability. For
example, in U.S. Pat. No. 3,897,783, issued to J. A. Ginocchio on
Aug. 5, 1975, the adhesive element provided therein terminated in
peaks which resulted in a decreased peeling force at the peaked
terminal portions. This adhesive pattern was applied by employing a
specifically designed adhesive applier. While this solution is
generally effective, it suffers from the drawback of requiring
intermittent application of adhesive, it is generally preferred in
high speed operations to perform such a step continuously.
Still another solution to the problem is to provide a product with
a so-called "dry edge". This method is exemplified in U.S. Pat. No.
3,672,371, issued on June 27, 1972 to R. J. Roeder and in U.S. Pat.
No. 3,881,490, issued on May 6, 1975 to H. A. Whitehead and R. V.
Braun. In both these instances, the adhesive element does not
extend the full longitudinal length of the product, but instead
ends some distance therefrom. On the other hand, the adhesive
element is covered by a protective strip which extends beyond the
ends of the adhesive element. Accordingly, prior to use the ends of
the release strip are not adhered to the adhesive and are free to
be gripped for removal. In use, the end portions of the product are
not adhered to the garment but instead, are also free to be gripped
for removal. While these unadhered ends do in fact allow for easier
peeling of both the release strip prior to use and of the product
from the undergarment during use, there are drawbacks. The release
strip is generally stiffer than the remainder of the product and so
the unadhered ends of the strip tend to stand away from the product
and tend to "catch" on each other so that the product cannot be
easily handled during production and packaging. This problem is
particularly acute in the products such as the so-called
three-dimensional curved garment liners as are described in a
commonly assigned U.S. patent application having a serial number
yet to be determined. The curvature of these napkins causes the
stiffer release strip material to stand away even further. During
use, the unadhered ends of the product provide a starting point for
the undesirable detachment and displacement of the entire product
under the forces exerted by body and garment movements.
It can thus be seen that, prior art efforts notwithstanding, a
completely satisfactory solution to the apparently conflicting
criteria in-use tenacity and easy peelability has heretofore been
unavailable.
SUMMARY OF THE INVENTION
In accordance with the present invention, an adhesively attached
protective absorbent liner for nether garments is provided uith
means for allowing the product to be tenaciously held in place
during use, but which can still be easily peeled to separate the
product from both the release strip and the garment, all without
the drawbacks encountered in prior art suggestions. The liner may
comprise a generally elongated absorbent body having a body
contacting major surface (i.e., the surface intended to be worn
against the body) and a garment contacting major surface, i.e., the
surface intended to be adhered to the crotch portion of a nether
garment. Means are provided for securing the liner to the nether
garment, these means comprising a pressure sensitive adhesive
element disposed longitudinally on the garment contacting surface
and extending substantially from end to end of that surface. A
removable protective release strip is provided overlying the
pressure sensitive element to protect the element from dirt and
unintentional adhesion prior to use. In accordance with the
teachings of this present invention, at least one extreme end
portion of the pressure sensitive adhesive element is provided with
a pattern of raised and depressed areas (i.e., raised and depressed
with respect to each other) whereby the resistance to peeling of
both the release strip and the nether garment is lower in this end
portion than in the central portions of the adhesive element.
Preferably both end portions are provided with such a pattern.
In perhaps its simplest embodiment, the adhesive element is
disposed on the garment contacting surface and is provided in its
end portions with the prescribed pattern of raised and depressed
areas by embossing these portions using an embossing roller having
such a pattern cut or etched into its surface. The release strip is
then applied to the adhesive element overlying both the end portion
and the unembossed central portion and will adhere to both portions
so as to lie against the product during production and packaging
without "catching" or otherwise getting in the way. Notwithstanding
this, it has been found that the release strip clings far less
tenaciously to the embossed areas than to the unembossed areas and
hence, the ends provide easy starting points for removing the
release stip. In fact, the strip may be removed for all practical
purposes with the same facility as the so-called "dry edge"
products but without any of the drawbacks. In use, the product may
be placed and adhered to the crotch portion of an undergarment and,
owing to the presence of adhesive extending to substantially the
very ends, the product will be adhered along its entire length
without leaving unadhered ends which could start the detachment of
the entire product. Notwithstanding this total longitudinal
adherenece, the embossed end portion will cling less tenaciously to
the fabric of the garment than the central unembossed portions and
hence, can be easily peeled therefrom thereby conveniently
providing a starting edge for gripping and peeling the remainder of
the product from the garment.
In a more specific embodiment, the embossing is extended across the
entire end of the product to include those areas adjacent to the
adhesive element. This extension of the embossing is, in fact, from
production point of view, easier to accomplish than limiting the
embossed areas to the adhesive and provides the additional
advantage of giving the embossed ends of the product z directional
strength, i.e., strength in the direction perpendicular to the
plane of the major surfaces.
Also described in detail herein is a method for manufacturing the
product of this invention without the need for fist embossing the
adhesive area and then applying the release strip. Instead, the
release strip is applied to the entire product assembly and the
ends of the product are embossed in such a manner as to leave the
release strip unembossed while still imprinting the embossing
pattern on the adhesive.
BRIEF DESCRIPTION OF THE INVENTION
Referrring to the drawings:
FIG. 1 is a perspective view looking down on the garment contacting
surface of an absorbent nether garment liner embodying the
teachings of this invention and showing the release strip partially
peeled therefrom;
FIG. 2 is a sectional view of the garment liner of FIG. 1 taken
along line 2--2;
FIG. 3 is a sectional view of the garment liner of FIG. 1 taken
along line 3--3;
FIG. 4 is a schematic longitudinal cross sectional view of a
portion of a machine line for producing the garment liner of this
invention;
FIG. 4A is a schematic, transverse cross sectional view of the
machine line FIG. 4 taken through line a--a; and
FIG. 4bis a perspective view of the top surface of the embossing
roll shown in FIG. 4a.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1-3 illustrate an exemplary embodiment of the invention.
Specifically depicted is an absorbent nether garment liner 10 with
the garment contacting major surface 12 facing upwardly in the
drawings and the body contacting major surface 14 facing
downwardly. The liner 10 comprises an absorbent body 16 which may
be made up of any suitable absorbent material such as, for example,
comminuted wood pulp fibers, cotton linters, rayon fibers, cotton
staple, blended sulfite creped wadding and the like. The absorbent
body may even comprise synthetic absorbent materials such as the
newly developed hydrophilic polyurethane foams. When employing
absorbent matter in loosely associated particulate form such as
comminuted wood pulp or crumbs of polyurethane foam, the
particulate matter should be enclosed in a wrapper material which
can be a fluid pervious woven material such as gauze, for example,
or a nonwoven material, such as the ones described in U.S. Pat. No.
3,554,788 issued on Jan. 12, 1971 to M. R. Fechillas which has the
added advantage of being flushable, i.e., may be disposed of by
dispersing and flushing away in a water closet. Typical absorbent
bodies comprising loosely associated absorbent particles enclosed
in a fluid pervious wrapper are described in the aforementioned
U.S. Pat. 3,897,783 issued to J. A. Ginocchio on Aug. 5, 1975.
In the absorbent body 16 illustrated in FIGS. 1-3, still another
form of absorbent material is employed by way of example, this
material being specifically the lofty and soft nonwoven
through-bonded fabric described in U.S. Pat. No. 3,663,238 issued
on May 16, 1972 to G. J. Liloia et al. This fabric consists
essentially of a mixture of approximately 25% by weight of long
(about 20.2 cms) rayon fibers and about 75% by weight of short
(about 0.02 cms) wood pulp fibers and has a water dispersible
binder applied throughout in an amount between about 1 percent and
about 30 percent of the weight of the fibers on a dry solids basis.
The binders of choice are of the self-curing acrylic latex family,
the urethane family or other binders which can be utilized in low
viscosity solutions or suspensions. The fabric has a weight of less
than about 8 ounces per square yard and a density of about 0.15
about 0.05 gm. per cc. and may be characterized as being absorbent
and extremely soft and lofty. Because of the through bonding, the
fabric is capable of maintaining its structural integrity without
the need of a wrapper material which, in the embodiment of FIGS.
1--3, has accordingly been dispensed with. As is best illustrated
in FIG. 3, a double thickness of the fabric is employed by folding
the longitudinal peripheral edges 18, 20 of a sheet of the fabric
toward the center to form the absorbent body 16. These edges may be
held in place by the application of adhesive or other means known
in the art (not shown).
Overlying and in juxtaposition with the garment contacting surface
of the absorbent body 16 is a fluid impervious layer 22 which is
provided to act as a barrier to body fluids and prevent the "strike
through" of such fluids onto the nether garment. This layer may
comprise any thin flexible impermeable material such as, for
example, a polymeric film, e.g., polyethylene, polypropylene,
cellophane or even a normally fluid pervious material that has been
treated to be impervious such as impregnated fluid repellent paper.
It will be appreciated by one skilled in the art that in the case
of the unwrapped, bonded fabric illustrated in FIGS. 1-3, the
impervious layer 22 is best applied on the garment contacting side
of the absorbent body 16 whereas, in the case of a wrapped product,
the impervious layer may also be placed between the absorbent
material and the wrapper or within the absorbent material. In some
instances, the impervious layer may make up a portion of the
wrapper itself as is the case in the product currently available
from the Personal Products Company of Milltown, N.J. and sold by
them as STAYFREE* Minipad sanitary napkins.
In any event, disposed upon the garment contacting major surface of
the absorbent body 16 is a longitudinally, centrally located
pressure sensitive adhesive element 24 which extends from one end
26 of the liner 10 to the other end 28 and is provided for
attaching the liner to a nether garment. This adhesive element may
comprise any of a large number of pressure sensitive adhesives
already available on the market, including, for example, the water
based pressure sensitive adhesives such as the acrylate adhesives,
for example, vinyl acetate-2ethyl hexyl acrylate copolymer which is
generally combined with tackifiers such as, for example, ethylene
amine. Alternatively, the adhesive may comprise the rapid-setting
thermoplastic (hot melt) adhesives such as block copolymers
exemplified by styrene and butadiene styrene copolymers. The
adhesive element may also comprise a two sided adhesive tape and
the advantages of this invention will accrue equally well to this
configuration.
In accordance with the teachings of this invention and as best
illustrated in FIG. 2, the end portions 27 and 29 of the adhesive
element 24 are provided with a pattern of raised areas 30 and
depressed areas 32. This pattern is best imposed upon the end
portions of the adhesive element by passing the ends of the liner
between an embossing roll and an anvil roll, as will be described
in greater detail below. In any event, in addition to imposing this
pattern upon the adhesive, the embossing process likewise imposes
such a pattern upon the areas of the liner 34 adjacent to the end
portion of the adhesive. This is particularly advantageous in that
such embossing gives these end portions a substantial increase in
resistance to delamination, a property highly desirable for the
ends of the liner which ends are generally gripped when applying
and removing the product. As best illustrated in FIG. 3, the
central portion of the liner and consequently, the central portion
36 of the adhesive element 24 are free of this embossed pattern of
raised and depressed areas and are essentially smooth and flat. The
pattern may comprise, for example, about 1-30% of the total
embossed area being raised and the remainder comprising the
depressed area. Preferably, the raised area comprises about 5-20%
of the total embossed area.
Overlying the full length of the adhesive element 24 is a
protective release strip 38 which is provided to protect the
adhesive element from dirt and from unintended adhesion prior to
use. The strip may be of any suitable sheet-like material which
adheres with sufficient tenacity to the adhesive element to remain
in place, but which can readily be removed when the liner is to be
used. A particularly useful material is a semibleached kraft paper,
the adhesive contacting side of which has been silicone coated to
provide for easy release from the adhesive element 24. As is shown
in FIG. 3, the release strip 38 makes close contact with the entire
surface of the unembossed central portion of the adhesive element
24. In contrast thereto, referring to FIG. 2, the release strip 38
tends to rest on only the raised areas 30 of the embossed end
portions of the adhesive. It has been discovered that the release
strip 38 will adhere to all portions of the adhesive element 24
with sufficient tenacity to allow for facile handling of the
product during production and prior to use. The tenacity of this
adherence, however, has been found to vary to a significant degree
between the embossed end portions and the unembossed central
portions, the latter portions being significantly more tenacious
than the former. Because of this lesser degree of adherence at the
ends of the liner, the release strip can be peeled away easily from
the embossed portions of the adhesive element 24. Once the peeling
of the release strip has been initiated, the partially peeled strip
can now be firmly gripped and completely peeled from the more
tenacious central portion of the adhesive element 24.
As has been described above, one method of obtaining the prescribed
pattern of raised and depressed areas in the end portions of the
adhesive is to pass the ends of the product through the nip of
embossing rollers. This can be done prior to applying the release
strip to the product and the described effect of having the release
strip rest predominantly upon the raised portions of the embossed
adhesive will be obtained. It is desirable, however, for the
purposes of high speed production, to form a long completed
laminate of all of the layers of the product, i.e., the absorbent
body, the adhesive element and the release strip, and then to cut
individual products from this laminate. Accordingly, a method has
also been provided for performing the prescribed embossing upon the
completed laminate (including the release) strip) without
concomittantly forcing the release strip into the depressed areas
of the embossed adhesive.
Referring now to FIG. 4, illustrated there is a schematic view of a
machine line employing such a method. A laminate 40 is moved from
left to right in the drawing in the direction of the arrow. The
laminate comprises the absorbent body 16 having the fluid
impervious layer 22 thereon. The pressure sensitive adhesive
element 24 is applied to the layer 22 and the release strip 38
overlies this adhesive element. The laminate 40 is passed through
the nip of two rotating rollers; an anvil roller 42 is and an
embossing roller 44. The anvil roller 42 is provided with a
substantially smooth surface 46 around its entire circumference
with the exception of an undercut portion 48, as best seen in FIG.
4a. The undercut portion 48 is of essentially the same width and
depth as the width and thickness of the release strip and is
adapted to accommodate the release strip 38 therein as the laminate
passes into the nip of the two rollers.
The embossing roller 44 is provided with an embossing section 50
which projects from the periphery of a portion of the circumference
of the roller 44 and is provided on its circumferential surface
with the desired pattern of raised and depressed area to be imposed
upon the laminate. Referrring to FIG. 4b shown there in perspective
view is the top surface of the embossing section. The pattern of
raised areas in this case take the form of truncated pyramids 43
whereas the depressed areas are the spaces 45 between pyramids. It
will be apparent to one skilled in the art that this is only one of
many possible patterns by which the benefits of this invention may
be obtained.
In operation, as the laminate is passed between the rollers, the
embossing rollers will impress the desired pattern upon the
laminate in space intervals determined by the portion of the
circumference of the roller 44 which is occupied by the embossing
section 50.
The rollers are spaced apart so that the distance between the flat
surface 46 of the anvil 42 and the surface 45 of the embossing
roller 44 which is not provided with the embossing section 50 is
approximately 0.1 to 0.2 inches thick and the release strip
approximately 0.001 to 0.008 inches thick. The rollers will be
spaced apart as described above a distance of about 0.01 to 0.02
inches or more. Normally, a nip pressure between the two rollers is
in the order of about 5,000 to 200,000 pounds per square inch and
may be developed for example, by spring loading one roller against
the other.
In operation, as the laminate is passed between the rollers, the
desired pattern will be impressed in spaced intervals, the spacing
of which is determined by the portion of the circumference of the
embossing roller 44 occupied by the embossing section 50. Because
the release strip 38 is accommodated within the undercut 48 of
roller 42, the strip is essentially uneffected by the embossing
operation. It has been discovered that even though only the
embossing roller is provided with the pattern of raised and
depressed areas and the anvil roller is provided with an
essentially flat surface, the pattern imposed upon the embossed
portion of the laminate is that illustrated in FIG. 2. That is to
say, both the top and bottom surfaces of the embossed portion of
the laminate after it leaves the nip of the embossing rolls exhibit
raised and depressed areas. The release strip, uneffected by the
embossing process, rests upon the raised areas, as is illustrated
in FIG. 2.
The laminate 40, leaving the nip of the embossing rollers and
having the embossing pattern imposed at intervals is next cut into
individual liners by cutting means (not shown) which pass
transversely through the embossed portions of the laminate. Such
cutting means, which form no part of the inventive features of this
invention may comprise any such means well known to those skilled
in the art, as for example, rotary knives or die cutters.
The advantages of this invention are further illustrated by the
following example.
EXAMPLE
A laminate is prepared in the form shown in FIG. 4 and is embossed
with the pattern illustrated in connection with this figure. The
absorbent body comprises the nonwoven fabric described in the
aforementioned U.S. Pat. No. 3,663,230. The fluid impervious layer
is a film of polyethylene having a thickness of 2 mils and the
adhesive is of the hot melt type. Approximately 10 percent of the
embossed adhesive area constitutes raised areas. The release strip
is the silicone coated paper described above. The laminate is
approximately two inches wide and 0.125 inches thick in the
unembossed areas. The embossed areas are approximately 0.035 inches
thick. The adhesive element is approximately 0.75 inches wide and
the release paper overlying the adhesive element is about 1.0
inches wide.
A series of five samples are cut from this partially embossed
laminate. Each of the samples comprise an unembossed length of 2.5
inches followed by an embossed length of 1.75 inches which in turn
is followed by an unembossed length of 2.5 inches. Each of these
samples is to be tested to determine the force required to
continuously peel the release strip from the remainder of the
sample. The test procedure used is to adhere each sample, garment
contacting side up, to a stainless steel plate by means of double
faced adhesive tape. A clip is then attached to the leading end of
the release strip, which clip is then in turn attached, by means of
a string, to the jaws of an Instron Tester. The string is so
arranged as to provide a peeling angle of 180.degree.. The jaws of
the Instron Tester are operated at a peeling rate of two inches per
minute and the Instron is equipped with a recorder-plotter which
plots the force-distance function of each peel test. The peeling is
carried out for all five samples and then the average force
recorded over all the umembossed adhesive areas for all of the
samples is determined by arithmetic averaging of the values read
from the plot.
The arithmetic average for all the embossed areas of the adhesive
is determined in the same manner. The test results are that the
average force for the embossed areas is 18.1 gms. as contrasted
with an average value of 84.9 gms. for the unembossed area. Thus,
it can be seen that the release strip clings far less tenaciously
to the embossed areas as compared to the unembossed areas. This
notwithstanding, the release strip clings to the embossed area to a
sufficiently tenacious degree to remain adhered thereto during
production and subsequent handling.
* * * * *